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Integumentary System
Inflammatory response
 http://www.sumanasinc.com/webcontent/anisamples/dynami
cillustrations/inflammatory.html
Something About Skin
 Skin is an organ of the body!
 Thinnest:
1/50 of an inch (eyelids and
eardrums)
 Thickest:
1/4 of an inch (soles of feet
and upper back)
 Blood vessels: 15 feet/inch
 Sweat pores: 2,000,000/square inch
 Oil glands: 2000/sq. inch
Something about skin
 Largest organ in the body
 10-15% of body weight
 Surface area of 1-2 meters
 Two main layers: epidermis, dermis
Face color?
 Pale Face: illness or fear
 Livid face: anger
 Blushing face; embarrassment
 Acne:
 What do you know about acne?
Functions of the Integumentary System
 Protection-protects underlying structures
 Sensation-skin receptors that detect pain, heat, etc.
 Vitamin D Production-skin produces vitamin d when
exposed to ultraviolet light
 Temperature Regulation-Helps
maintain a body temperature of about 37
degrees C
 Excretion- removes waste products from the body
Vitamin D Production
 Ultraviolet light stimulates the production of a precursor
molecule in the skin that is modified by the liver and kidneys
into vitamin D.
 Vitamin D increases calcium uptake in the intestines.
Hypodermis
 Attaches underlying bone and muscle and supplies it with
blood vessels and nerves
 Also called the subcutaneous tissue
 Can be used to estimate total body fat (thickness of skin)
 The site of subcutaneous injections
Dermis
 Layer of dense connective tissue
 Contains fibroblasts, fat cells, and macrophages
 Collagen and elastic fibers
 Gives the structural strength to the skin
– Produce cleavage or tension lines in the skin
 Striae/stretch marks
– If the skin is overstretched, the skin can be damaged
– lines that are visible through the epidermis
 Dermal Papillae
– Projections extending toward the epidermis
– In palms, feet, and tips of digits
– Curving ridges that shape the overlying epidermis into
fingerprints and footprints
Epidermis
 Layer of epithelial tissue that rests on the dermis
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Stratified squamous epithelium
Keratinization
Cells become filled with protein keratin
Has distinct layers of strata:
1. Stratum basale-deepest stratum
2. Stratum corneum-outer layer
Skin Color
 Determined by pigments in the skin
 Melanin: group of pigments responsible for skin, hair, and
eye color
 Melanocytes: produce melanin
 Amount of melanin: determined by location and severity of
the sun
 Albinism is a recessive genetic trait that causes a deficiency
or absence of melanin
Hair
 The shaft of hair protrudes above the surface of the skin
 The root and hair bulb are below the surface
 A hard cortex surrounds a soft center (medulla)
 Cortex is covered by the cuticle
 Hair follicle: an extension of the epidermis deep into the
dermis
Hair Growth
 Produced in cycles
 Growth stage and a resting stage
 The hair grows longer as cells are added at the base of the
hair root
 The hair loss: the hair is being replaced
 Eye lashes grow for about 30 days and rest for 1-2 years
 Scalp hairs grow for a period of 3 years and rest for 1-2
years
Hair Loss
 Most common permanent hair loss: pattern baldness
 Hair follicles are lost
 Remaining hair follicles revert to producing vellus hair
(transparent and short)
 Genetics and hormone testosterone are responsible for it
 Hair growth rate: 0.3 mm/day
Accessory Structures
Muscles
 Arrector pili: smooth muscle cells
 associated with each hair follicle
– Cause hair to “stand on end” or more perpendicular to
the skin
Glands
Sebaceous glands
Sebum -oily, white substance (lipids)
Sweat glands
Merocrine sweat glands –open on surface of skin, watery
secretion (palms and soles, cools the body)
Apocrine sweat glands -open into hair follicle, thick organic
secretion (underarms; body odor)
Nails
 The nail is a thin plate, consisting of layers of dead stratum
corneum cells
 The nail body: the visible part of the nail
 Nail root: covered by the skin
 The eponychium (cuticle): stratum corneum that extends
onto the nail body
 The nail root and nail body attach to the nail matrix
 The lunula: seen through the nail body
 The nail matrix produces the nail, which is stratum corneum
containing hard keratin.
Effects of Aging
 Blood flow is reduced
 the skin becomes thinner and appears more transparent
 The number of melanocytes generally decreases
 increase in spots producing age spots
The Integumentary System as a Diagnostic Aid
 Useful in diagnosis because it is easily observed and reflects
events occurring in the body
– Cyanosis-skin turns bluish due to a decreased oxygen
content
– Jaundice-indicates liver damage and skin turns yellow
Burns
 First-degree, second-degree, or third-degree
 First-degree burns: only the epidermis is damaged
 Second-degree burns: damage the epidermis and dermis
 Third-degree burns: completely destroy the dermis and
epidermis
Skin Cancer
 The most common type of cancer
 Most skin cancers develop on the face, neck, or hands
 Most deadly type of skin cancer: melanoma
 Arises from the melanocytes, usually in a preexisting mole
Basal Cell Carcinoma
 Most frequent skin cancer
 Begins in the stratum basale cells and extends into the
dermis
 Produces an open ulcer
 Little danger that this cancer will spread to other parts
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Squamous cell carcinoma
 Develops from cells immediately superficial to the stratum
basale
 Normally these cells undergo little or no cell division
 In Sq. Cell Car. the cells continue to divide as they produce
keratin
 Results in nodular, keratinized tumor in the epidermis
 It can invade dermis, metastasize and cause death
Malignant melanoma
 Rare form of skin cancer
 Arises from melanocytes
 In a preexisting mole
 A mole is an aggregation of melanocytes
 If untreated, this cancer can be fatal